Conventional microfluidic chips for capillary electrophoresis typically provide a carrier channel in which substances within a sample are electrophoretically separated and detected and a sample channel which intersects with the carrier sample for introduction of samples into the carrier channel. Typically, the carrier channel is fluidicly disposed between a pair of carrier fluid reservoirs and the sample channel is disposed between a pair of sample reservoirs. A sample fluid containing substances for separation can be introduced into a sample reservoir and the carrier fluid which provides an electrically conductive medium is introduced into a carrier reservoir manually by dropper, syringe, or the like. The sample fluid and the carrier fluid typically flow through the network of channels by capillary action, external pressure or electro-osmotic flow.
A voltage in the range of few hundred volts and sometimes above a thousand volts can be applied between the reservoirs through electrical probes. This induces an electro-osmotic flow which can be used to entrain a small amount of the sample fluid into the carrier channel at the intersection of the two channels. The various charged substances in the small amount of sample will separate in the carrier channel as a consequence of differences in electrophoretic mobility. At a certain location, the fluid in the carrier channel may be interrogated either optically or electrically. Due to separation of the various substances within the carrier channel each can pass the detection location at different times. This provides a means for resolving the various substances within the sample.
While conventional microfluidic chips for capillary electrophoresis may efficiently separate certain substances within a sample fluid, the conventional handling, timing and delivery of sample fluids, carrier fluids or other fluids to flow paths of the microfluidic chip, and particularly the manual transfer of fluids to the corresponding reservoirs of the microfluidic chip, precludes an automated capillary electrophoresis system for sample analysis.